Effect of FeO content on migration and distribution of chromium in glass ceramics derived from stainless steel slag and chromium fixation

In this paper, glass-ceramics were prepared from stainless steel slag, and the effects of FeO content on the occurrence and distribution of Cr in glass-ceramics, migration behavior and chromium fixation were systematically studied. The results showed that the amount of crystal nucleus of Cr-spinel increased, and then Cr in the glass phase gradually migrated to Cr-spinel with the increase of FeO content in the nucleation stage. In the crystallization stage, Cr-spinel nanocrystals generated diopside crystal phase. TEM and XPS analysis showed that part of Cr occurred in the crystal lattice of diopside, and the other part of Cr still existed in the Cr-spinel encapsulated by diopside. The Cr in the glass phase also diffused and migrated into the crystal lattice of diopside with the formation of diopside crystals. When the content of FeO was 4.80%(w/w), 95.23% (w/w) Cr occurred in the crystal phase of diopside. The leaching concentration of Cr³⁺ was only 0.007 mg/L, and the compressive and Vickers hardness strength of glass-ceramics were 235 MPa and 949.3, respectively. The research results provide theoretical and technical support for strengthening chromium fixation, realizing harmless and high-value utilization of stainless steel slag.